Nasal nitric oxide screening for primary ciliary dyskinesia: systematic review and meta-analysis

Nasal Disorders

Nasal obstruction, rhinorrhea, and epistaxis are common presenting concerns in primary care clinics. Nasal disorders affect the quality of life for many children and families. Rarely, these complaints may represent a life-threatening condition among infant obligate nasal breathers or cases of unusual pathology. The most common causes of rhinorrhea and nasal obstruction vary by age and include physiologic, infectious, allergic, foreign body, irritant, and traumatic causes. Less commonly, children may have congenital malformations, sinonasal masses, or autoimmune disease. The most common causes of epistaxis are inflammatory, environmental, and traumatic causes and medication misuse, but rarely, children may have predisposing anatomic, hematologic, or vascular abnormalities or even sinonasal tumors. In this article, we provide a thorough review of the common nasal disorders treated every day in primary care clinics and mention briefly some of the rare but serious cases that may be overlooked without considering a full differential diagnosis.

Lack of CFAP54 causes primary ciliary dyskinesia in a mouse model and human patients

Primary ciliary dyskinesia (PCD) is a highly heterogeneous recessive inherited disorder. FAP54, the homolog of CFAP54 in Chlamydomonas reinhardtii, was previously demonstrated as the C1d projection of the central microtubule apparatus of flagella. A Cfap54 knockout mouse model was then reported to have PCD-relevant phenotypes. Through whole-exome sequencing, compound heterozygous variants c.2649_2657delinC (p. E883Dfs*47) and c.7312_7313insCGCAGGCTGAATTCTTGG (p. T2438delinsTQAEFLA) in a new suspected PCD-relevant gene, CFAP54, were identified in an individual with PCD. Two missense variants, c.4112A>C (p. E1371A) and c.6559C>T (p. P2187S), in CFAP54 were detected in another unrelated patient. In this study, a minigene assay was conducted on the frameshift mutation showing a reduction in mRNA expression. In addition, a CFAP54 in-frame variant knock-in mouse model was established, which recapitulated the typical symptoms of PCD, including hydrocephalus, infertility, and mucus accumulation in nasal sinuses. Correspondingly, two missense variants were deleterious, with a dramatic reduction in mRNA abundance from bronchial tissue and sperm. The identification of PCD-causing variants of CFAP54 in two unrelated patients with PCD for the first time provides strong supportive evidence that CFAP54 is a new PCD-causing gene. This study further helps expand the disease-associated gene spectrum and improve genetic testing for PCD diagnosis in the future.

Role of Nasal Nitric Oxide in Primary Ciliary Dyskinesia and Other Respiratory Conditions in Children

Nitric oxide (NO) is produced within the airways and released with exhalation. Nasal NO (nNO) can be measured in a non-invasive way, with different devices and techniques according to the age and cooperation of the patients. Here, we conducted a narrative review of the literature to examine the relationship between nNO and some respiratory diseases with a particular focus on primary ciliary dyskinesia (PCD). A total of 115 papers were assessed, and 50 were eventually included in the review. nNO in PCD is low (below 77 nL/min), and its measurement has a clear diagnostic value when evaluated in a clinically suggestive phenotype. Many studies have evaluated the role of NO as a molecular mediator as well as the association between nNO values and genotype or ciliary function. As far as other respiratory diseases are concerned, nNO is low in chronic rhinosinusitis and cystic fibrosis, while increased values have been found in allergic rhinitis. Nonetheless, the role in the diagnosis and prognosis of these conditions has not been fully clarified.

Ciliary dyskinesia in severe asthma is not affected by chronic mucus hypersecretion

Chronic mucus hypersecretion (CMH) is linked to increased asthma severity. Ciliary dyskinesia is present in severe asthma but CMH was not associated with a worse ciliary dysfunction, suggesting another mechanism to explain chronic cough and phlegm. https://bit.ly/3JNUgGr.

Nasal Nitric Oxide as a Biomarker in the Diagnosis and Treatment of Sinonasal Inflammatory Diseases: A Review of the Literature

OBJECTIVE

To critically review the literature on nasal nitric oxide (nNO) and its current clinical and research applicability in the diagnosis and treatment of different sinonasal inflammatory diseases, including acute bacterial rhinosinusitis (ABRS), allergic rhinitis (AR), and chronic rhinosinusitis (CRS).

METHODS

A search of the PubMed database was conducted to include articles on nNO and sinonasal diseases from January 2003 to January 2020. All article titles and abstracts were reviewed to assess their relevance to nNO and ABRS, AR, or CRS. After selection of the manuscripts, full-text reviews were performed to synthesize current understandings of nNO and its applications to the various sinonasal inflammatory diseases.

RESULTS

A total of 79 relevant studies from an initial 559 articles were identified using our focused search and review criteria. nNO has been consistently shown to be decreased in ABRS and CRS, especially in cases with nasal polyps. While AR is associated with elevations in nNO, nNO levels have also been found to be lower in AR cases with higher symptom severity. The obstruction of the paranasal sinuses is speculated to be an important variable in the relationship between nNO and the sinonasal diseases. Treatment of these diseases appears to affect nNO through the reduction of inflammatory disease burden and also mitigation of sinus obstruction.

CONCLUSION

nNO has been of increasing interest to researchers and clinicians over the last decade. The most compelling data for nNO as a clinical tool involve CRS. nNO can be used as a marker of ostiomeatal complex patency. Variations in measurement techniques and technology continue to impede standardized interpretation and implementation of nNO as a biomarker for sinonasal inflammatory diseases.

The Palestinian primary ciliary dyskinesia population: first results of the diagnostic and genetic spectrum

Background

Diagnostic testing for primary ciliary dyskinesia (PCD) started in 2013 in Palestine. We aimed to describe the diagnostic, genetic and clinical spectrum of the Palestinian PCD population.

Methods

Individuals with symptoms suggestive of PCD were opportunistically considered for diagnostic testing: nasal nitric oxide (nNO) measurement, transmission electron microscopy (TEM) and/or PCD genetic panel or whole-exome testing. Clinical characteristics of those with a positive diagnosis were collected close to testing including forced expiratory volume in 1 s (FEV₁) Global Lung Index z-scores and body mass index z-scores.

Results

68 individuals had a definite positive PCD diagnosis, 31 confirmed by genetic and TEM results, 23 by TEM results alone, and 14 by genetic variants alone. 45 individuals from 40 families had 17 clinically actionable variants and four had variants of unknown significance in 14 PCD genes. CCDC39, DNAH11 and DNAAF11 were the most commonly mutated genes. 100% of variants were homozygous. Patients had a median age of 10.0 years at diagnosis, were highly consanguineous (93%) and 100% were of Arabic descent. Clinical features included persistent wet cough (99%), neonatal respiratory distress (84%) and situs inversus (43%). Lung function at diagnosis was already impaired (FEV₁ z-score median -1.90 (-5.0-1.32)) and growth was mostly within the normal range (z-score mean -0.36 (-3.03-2.57). 19% individuals had finger clubbing.

Conclusions

Despite limited local resources in Palestine, detailed geno- and phenotyping forms the basis of one of the largest national PCD populations globally. There was notable familial homozygosity within the context of significant population heterogeneity.

Identification of novel biallelic LRRC6 variants in male Chinese patients with primary ciliary dyskinesia and infertility

PURPOSE

The aim of this study is to identify the genetic cause of primary ciliary dyskinesia (PCD) and male infertility in two unrelated Han Chinese families.

METHODS

We performed whole-exome sequencing in two unrelated male Han Chinese patients suffering from infertility and PCD to identify the pathogenic variants. Ultrastructural and immunostaining analyses of patient's spermatozoa were performed to characterize the effect of the variants. The pathogenicity of the variants was validated using patient's spermatozoa by western blotting and immunostaining analysis. Intracytoplasmic sperm injection (ICSI) was conducted in the affected families.

RESULTS

Three variants in leucine-rich repeat containing 6 (LRRC6) [patient 1(compound heterozygote): NM_012472: c.538C > T, (p.R180*) and c.64dupT, (p.S22Ffs*19); patient 2 (homozygote): c.863C > A, (p.P288H)] were identified in two unrelated patients with PCD and male infertility. These variants were predicated deleterious and were absent or rare in human population genome data. LRRC6-mutant spermatozoa showed a highly aberrant morphology and ultrastructure with lacked inner and outer dynein arms. The LRRC6 protein was present along the normal sperm flagella, and was significantly decreased in the mutated spermatozoa. Interestingly, both patients were able to conceive through ICSI and birthed a healthy baby.

CONCLUSION

Our results extend the LRRC6 variant spectrum and provide reproductive guidance to families suffering from PCD-linked infertility caused by LRRC6 variants.

Progress in diagnosis of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive genetic disorder characterised by motor ciliary dysfunction. The main manifestations are bronchiectasis, chronic sinusitis and situs inversus (viscera translocation triad). Additionally, it can present as male infertility and female ectopic pregnancy. However, there is currently no recognised diagnostic standard for PCD, which brings great challenges to its diagnosis and treatment. In addition to clinical data, the current diagnostic methods of PCD mainly include PICADAR, nasal exhaled nitric oxide, transmission electron microscopy, high-resolution immunofluorescence, high-speed video microscopy analysis and gene detection. This article makes a comprehensive comparison of the above diagnostic methods and suggests that genetic detection technology will become the general trend of PCD diagnosis.

Identification of a Novel OFD1 Variant in a Patient with Primary Ciliary Dyskinesia

Background

OFD1 encodes a protein with 1012 amino acids, which is a component of basal bodies and centrioles, essential for cilia biogenesis. OFD1 was reported to be associated with X-chromosome linked dysmorphology syndrome in early studies and recent studies reported a few cases with primary ciliary dyskinesia (PCD) caused by OFD1 deficiency.

Case Presentation

We report a 31-year-old man who suffered from recurrent respiratory infections with typical manifestations of primary ciliary dyskinesia. In addition to respiratory manifestations, the patient also had situs inversus, obesity, gastroesophageal reflux, and hearing impairment. Clubbing fingers and mild streblomicrodactyly were also observed.

Examination Result

We performed whole-exome sequencing to identify a novel variant c.2795delA:p.(Lys932Argfs*3) in OFD1. The hemizygous variant was predicted to be likely pathogenic by bioinformatic analysis software and ACMG guideline. High-speed video microscopy (HSVM), transmission electron microscopy (TEM), and immunofluorescence were performed to analyze the respiratory cilia. A high beating frequency and a stiff beating pattern were observed under HSVM, while there were no significant abnormalities in TEM and immunofluorescence. The sperm flagella examinations were also generally normal.

Conclusion

Our study identified a novel frameshift variant in OFD1 causing PCD, enriched the genetic spectrum of OFD1 variants, and verified that OFD1 mutation can lead to only a PCD characteristic phenotype, while other OFD1-associated syndromic symptoms such as dysmorphic features and renal symptoms were not present.

Novel RSPH4A Variants Associated With Primary Ciliary Dyskinesia-Related Infertility in Three Chinese Families

Background: The radial spoke head component 4A (RSPH4A) is involved in the assembly of radial spokes, which is essential for motile cilia function. Asthenoteratozoospermia in primary ciliary dyskinesia (PCD) related to RSPH4A variants has not been reported. Materials and Methods: RSPH4A variants were identified and validated using whole-exome and Sanger sequencing in three unrelated Chinese families. High-speed video microscopy analysis (HSVA) was performed to measure the beating frequency and pattern of nasal cilia of the patients and healthy control. Papanicolaou staining and computer-aided sperm analysis were performed to analyze the morphology and motility of the sperm in patient 1. Immunofluorescence was adopted to confirm the structure deficiency of sperm and nasal cilia. Results: Patient 1 from family 1 is a 22-year-old unmarried male presented with bronchiectasis. Semen analysis and sperm Papanicolaou staining confirmed asthenoteratozoospermia. Novel compound heterozygous RSPH4A variants c.2T>C, p.(Met1Thr) and c.1774_1775del, p.(Leu592Aspfs*5) were detected in this patient. Patients 2 and 3 are from two unrelated consanguineous families; they are both females and exhibited bronchiectasis and infertility. Two homozygous RSPH4A variants c.2T>C, p.(Met1Thr) and c.351dupT, p.(Pro118Serfs*2) were detected, respectively. HSVA showed that most of the cilia in patients 1 and 3 were with abnormal rotational movement. The absence of RSPH4A and RSPH1 in patient 1's sperm and patient 3's respiratory cilia was indicated by immunofluorescence. Patient 2 died of pulmonary infection and respiratory failure at the age of 35 during follow-up. Conclusion: Dysfunctional sperm flagellum and motile cilia in the respiratory tract and the fallopian tube were found in patients with RSPH4A variants. Our study enriches the genetic spectrum and clinical phenotypes of RSPH4A variants in PCD, and c.2T>C, p.(Met1Thr) detected in our patients may be a hotspot RSPH4A variant in Chinese.

An international survey on nasal nitric oxide measurement practices for the diagnosis of primary ciliary dyskinesia

Nasal nitric oxide (nNO) measurements are routinely used in the assessment of patients suspected to have primary ciliary dyskinesia (PCD), but recommendations for performing such measurements have not focused on children and do not include all current practices. To guide the development of a European Respiratory Society-supported technical standard for nNO measurements in children, an international online survey was conducted to better understand current practices for measuring nNO among providers involved in PCD diagnostics.

Seventy-eight professionals responded, representing 65 centres across 18 countries, mainly located in Europe and North America. Nearly all centres measured nNO in children and more than half of them performed measurements before 5-years of age. The test was often postponed in children with signs of acute airway infection. In Europe, the electrochemical technique was more frequently used than chemiluminescence. A similar proportion of centres performed measurements during exhalation against a resistance (49/65) or during tidal breathing (50/65) with 15 centres using only exhalation against a resistance and 15 centres using only tidal breathing. The cut-off values used to discriminate PCD was consistent across centres using chemiluminescence analyzers and these centres reported results as an output (nL.min−1). However, cut-off values were highly variable across centres using electrochemical devices, and nNO concentrations were typically reported as ppb.

This survey represents the first to determine real-world use of nNO measurements worldwide and revealed remarkable variability in methodology, equipment, and interpretation. These findings will be useful to standardise methods and training.

Limitations of Nasal Nitric Oxide Measurement for Diagnosis of Primary Ciliary Dyskinesia with Normal Ultrastructure

Rationale Primary ciliary dyskinesia (PCD) is a heterogeneous, multisystem disorder characterized by defective ciliary beating. Diagnostic guidelines of the American Thoracic Society (ATS) and European Respiratory Society (ERS) recommend measurement of nasal nitric oxide (nNO) for PCD diagnosis. Several studies demonstrated low nNO-production rates in PCD individuals but underlying causes remain elusive. Objective To determine nNO-production rates in a well-characterized PCD cohort including subgroup analyses with regard to ultrastructural and ciliary beating phenotypes. Methods This study included 301 individuals assessed according to ERS guidelines. Diagnostic cutoffs for nNO-production rates for this study cohort and subgroups with normal and abnormal ultrastructure were determined. Diagnostic accuracy was also tested for the widely used 77 nl/min-cutoff in this study cohort. The relationship between nNO-production rates and ciliary beat frequencies (CBFs) was evaluated. Results The study cohort comprised 180 individuals with definite PCD diagnosis including 160 individuals with genetic diagnosis, 16 individuals with probable PCD diagnosis and 105 disease controls. The 77 nl/min nNO-cutoff showed a test sensitivity of 0.92 and specificity of 0.86. Test sensitivity was lower (0.85) in the subgroup of 47 PCD individuals with normal ultrastructure compared to 133 PCD individuals with abnormal ultrastructure (0.95). The optimal diagnostic cutoff for the nNO-production rate for the whole study cohort was 69.8 nl/min (sensitivity 0.92, specificity 0.89), however it was 107.8 nl/min (sensitivity 0.89, specificity 0.78) for the subgroup of PCD with normal ultrastructure. PCD individuals with normal ultrastructure compared to abnormal ultrastructure showed higher ciliary motility. Consistently, PCD individuals with higher CBFs showed higher nNO-production rates. In addition, laterality defects occurred less frequently in PCD with normal ultrastructure. Conclusion Measurements of nNO below the widely used 77 nL/min cutoff are less sensitive in detecting PCD individuals with normal ultrastructure. Our findings indicate, that higher nNO-production in this subgroup with a higher cutoff for the nNO-production rate (107.8 nl/min) and higher residual ciliary motility are dependent on the underlying molecular PCD defect. Higher nNO-production rates, higher residual CBFs and the lower prevalence of laterality defects hamper diagnosis of PCD with normal ultrastructure. Adjusting the cutoff of nNO-production rate to 107.8 nl/min might promote diagnosing PCD with normal ultrastructure.

A Novel Homozygous Variant in GAS2L2 in Two Sisters with Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a rare hereditary disease. We herein report two sisters in their 20s with suspected PCD. They were both born at full term and did not have situs inversus. Chest computed tomography showed similar signs of bronchiectasis in both siblings. Genetic examinations of the family confirmed that the sisters both harbored a homozygous variant in the growth-arrest-specific 2-like 2 (GAS2L2) gene. This is the third report of a family with PCD caused by a GAS2L2 variant.

Feasibility of nasal NO screening in healthy newborns

BACKGROUND

Nasal nitric oxide (nNO) measurement is recommended as a first line screening test for primary ciliary dyskinesia (PCD). While reliable velum- and non-velum-closure techniques exist for preschool children and older individuals, no data are available for neonates.

AIMS

To determine feasibility of nNO screening and nNO concentration in healthy newborns in the first week of life.

METHODS

Nasal NO was analyzed in tidal breathing during natural sleep using a CLD-88 sp NO analyzer (chemoluminescence sensor) and a NIOX MINO (electrochemical sensor). Test success and nNO concentration were determined and compared between the two devices.

RESULTS

Nasal NO was measured in 62 healthy neonates within the first week of life. Feasibility of nNO measurement was 100% for at least one nostril and 85.5% for both nostrils using the chemoluminescence device, but significantly lower with the electrochemical device (85.5% and 53.2%; p < .001). Median nNO concentration was 38 ppb (interquartile range, 27-55; range, 9-100) with the ECOMEDICS device and 23 (15-33, 8-59) with the NIOX MINO (p < .001), with a trend towards higher values for older subjects. None of the subjects exceeded nNO levels of 100 ppb.

CONCLUSION

Measurement of nNO using a chemoluminescence device is highly feasible in newborns during natural sleep. However, nNO levels are considerably lower compared to the published data for older individuals and in the range of a PCD reference group of infants between 4 and 8 weeks of age, potentially resulting in a great overlap with subjects with PCD in this age group. Therefore, screening for PCD using nasal NO might not be useful in the first week of life. Upon clinical suspicion, other diagnostic tests such as high-speed video analysis of the cilia should be applied.

Impact of Motile Ciliopathies on Human Development and Clinical Consequences in the Newborn

Motile cilia are hairlike organelles that project outward from a tissue-restricted subset of cells to direct fluid flow. During human development motile cilia guide determination of the left-right axis in the embryo, and in the fetal and neonatal periods they have essential roles in airway clearance in the respiratory tract and regulating cerebral spinal fluid flow in the brain. Dysregulation of motile cilia is best understood through the lens of the genetic disorder primary ciliary dyskinesia (PCD). PCD encompasses all genetic motile ciliopathies resulting from over 60 known genetic mutations and has a unique but often underrecognized neonatal presentation. Neonatal respiratory distress is now known to occur in the majority of patients with PCD, laterality defects are common, and very rarely brain ventricle enlargement occurs. The developmental function of motile cilia and the effect and pathophysiology of motile ciliopathies are incompletely understood in humans. In this review, we will examine the current understanding of the role of motile cilia in human development and clinical considerations when assessing the newborn for suspected motile ciliopathies.

Diagnosis of primary ciliary dyskinesia: discrepancy according to different algorithms

Background

Diagnosis of primary ciliary dyskinesia (PCD) is challenging since there is no gold standard test. The European Respiratory (ERS) and American Thoracic (ATS) Societies developed evidence-based diagnostic guidelines with considerable differences.

Objective

We aimed to compare the algorithms published by the ERS and the ATS with each other and with our own PCD-UNIBE algorithm in a clinical setting. Our algorithm is similar to the ERS algorithm with additional immunofluorescence staining. Agreement (Cohen's κ) and concordance between the three algorithms were assessed in patients with suspicion of PCD referred to our diagnostic centre.

Results

In 46 out of 54 patients (85%) the final diagnosis was concordant between all three algorithms (30 PCD negative, 16 PCD positive). In eight patients (15%) PCD diagnosis differed between the algorithms. Five patients (9%) were diagnosed as PCD only by the ATS, one (2%) only by the ERS and PCD-UNIBE, one (2%) only by the ATS and PCD-UNIBE, and one (2%) only by the PCD-UNIBE algorithm. Agreement was substantial between the ERS and the ATS (κ=0.72, 95% CI 0.53–0.92) and the ATS and the PCD-UNIBE (κ=0.73, 95% CI 0.53–0.92) and almost perfect between the ERS and the PCD-UNIBE algorithms (κ=0.92, 95% CI 0.80–1.00).

Conclusion

The different diagnostic algorithms lead to a contradictory diagnosis in a considerable proportion of patients. Thus, an updated, internationally harmonised and standardised PCD diagnostic algorithm is needed to improve diagnostics for these discordant cases.

There is no gold standard test for diagnosing PCD. The use of existing diagnostic algorithms leads to contradicting results in many patients (15% in this study). Thus, an updated and internationally harmonised diagnostic guideline is needed.https://bit.ly/2U19Vvq

Ciliary Dyneins and Dynein Related Ciliopathies

Although ubiquitously present, the relevance of cilia for vertebrate development and health has long been underrated. However, the aberration or dysfunction of ciliary structures or components results in a large heterogeneous group of disorders in mammals, termed ciliopathies. The majority of human ciliopathy cases are caused by malfunction of the ciliary dynein motor activity, powering retrograde intraflagellar transport (enabled by the cytoplasmic dynein-2 complex) or axonemal movement (axonemal dynein complexes). Despite a partially shared evolutionary developmental path and shared ciliary localization, the cytoplasmic dynein-2 and axonemal dynein functions are markedly different: while cytoplasmic dynein-2 complex dysfunction results in an ultra-rare syndromal skeleto-renal phenotype with a high lethality, axonemal dynein dysfunction is associated with a motile cilia dysfunction disorder, primary ciliary dyskinesia (PCD) or Kartagener syndrome, causing recurrent airway infection, degenerative lung disease, laterality defects, and infertility. In this review, we provide an overview of ciliary dynein complex compositions, their functions, clinical disease hallmarks of ciliary dynein disorders, presumed underlying pathomechanisms, and novel developments in the field.

Nasal nitric oxide testing for allergic rhinitis patients: Systematic review and meta-analysis

BACKGROUND

Nasal nitric oxide (nNO) levels in allergic rhinitis (AR), healthy people or nonallergic rhinitis (NAR) have shown contradicting results in previous studies. By meta-analysis, we reviewed studies that measured nNO in AR patients to assess nNO's ability to discriminate AR from healthy people or NAR.

METHODS

We systematically searched PubMed, Cochrane, Embase, Ovid, Web of Science, Wanfang Data, CNKI until December 15, 2020. Differences were expressed as standardized mean differences (SMD) with 95% confidence interval (CI), by random-effects method.

RESULTS

A total of 10 original studies with 561 AR patients, 327 healthy controls, 123 NAR patients were included in the narrative synthesis and 9 studies in the meta-analysis. nNO in AR was significantly increased compared with healthy controls (SMD: 0.989; 95% CI: 0.402, 1.576; p = .001) or NAR (SMD: 0.680; 95% CI: 0.101, 1.259; p = 0.021). However, subgroup analysis based on measuring process and patient characteristics showed that no significant differences were detected in nNO between AR patients with nasal polyps or sinusitis or marked ostial obstruction and healthy controls.

CONCLUSIONS

nNO is a potential indicator for recognizing AR. Nasal polyps, sinusitis and marked ostial obstruction should be considered before nNO is applied to detect AR.

Oxidative Stress and Endoplasmic Reticulum Stress in Rare Respiratory Diseases

Several studies have shown that some rare respiratory diseases, such as alpha-1 antitrypsin deficiency (AATD), idiopathic pulmonary fibrosis (IPF), cystic fibrosis (CF), and primary ciliary dyskinesia (PCD) present oxidative stress (OS) and endoplasmic reticulum (ER) stress. Their involvement in these pathologies and the use of antioxidants as therapeutic agents to minimize the effects of OS are discussed in this review.

Nasal Nitric Oxide Measurement in Primary Ciliary Dyskinesia. A Technical Paper on Standardized Testing Protocols

Nasal nitric oxide concentrations are extremely low in primary ciliary dyskinesia (PCD), and measurement of this nasal gas is recommended as a PCD diagnostic test in cooperative patients aged 5 years and older. However, nasal nitric oxide measurements must be performed with chemiluminescence analyzers using a standardized protocol to ensure proper results, because nasal nitric oxide values can be influenced by various internal and external factors. Repeat nasal nitric oxide testing on separate visits is required to ensure that low diagnostic values are persistent and consistent with PCD. This technical paper presents the standard operating procedures for nasal nitric oxide measurement used by the PCD Foundation Clinical and Research Centers Network at various specialty centers across North America. Adherence to this document ensures reliable nasal nitric oxide testing and high diagnostic accuracy when employed in a population with appropriate clinical phenotypes for PCD.

Motile ciliopathies

Motile cilia are highly complex hair-like organelles of epithelial cells lining the surface of various organ systems. Genetic mutations (usually with autosomal recessive inheritance) that impair ciliary beating cause a variety of motile ciliopathies, a heterogeneous group of rare disorders. The pathogenetic mechanisms, clinical symptoms and severity of the disease depend on the specific affected genes and the tissues in which they are expressed. Defects in the ependymal cilia can result in hydrocephalus, defects in the cilia in the fallopian tubes or in sperm flagella can cause female and male subfertility, respectively, and malfunctional motile monocilia of the left-right organizer during early embryonic development can lead to laterality defects such as situs inversus and heterotaxy. If mucociliary clearance in the respiratory epithelium is severely impaired, the disorder is referred to as primary ciliary dyskinesia, the most common motile ciliopathy. No single test can confirm a diagnosis of motile ciliopathy, which is based on a combination of tests including nasal nitric oxide measurement, transmission electron microscopy, immunofluorescence and genetic analyses, and high-speed video microscopy. With the exception of azithromycin, there is no evidence-based treatment for primary ciliary dyskinesia; therapies aim at relieving symptoms and reducing the effects of reduced ciliary motility.

Clinical application of nasal nitric oxide measurement in allergic rhinitis: A systematic review and meta-analysis

BACKGROUND

Nasal nitric oxide (nNO) is considered a biomarker of nasal inflammation.

OBJECTIVE

To perform a systematic review with meta-analysis and meta-regressions on the association between nNO levels and allergic rhinitis (AR).

METHODS

PubMed, Web of Science, Scopus, and EMBASE databases were systematically searched. Differences between cases and controls were expressed as standardized mean differences (SMD) with 95% confidence intervals (CI).

RESULTS

Overall, 39 articles were included: 30 containing data on nNO measured by nasal aspiration (1881 patients with AR and 1337 controls) and 12 assessing nNO by nasal exhalation (525 patients with AR and 350 controls). Compared with controls, AR presented significantly higher nNO values both during nasal aspiration (SMD, 1.309; 95% CI, 0.841-1.777; P < .001) and nasal exhalation (SMD, 0.708; 95% CI, 0.303-1.114; P = .001). Sensitivity and subgroup analyses confirmed that the results for the evaluated outcomes were not affected by the presence of clinical confounding factors (asthma, nasal polyps, inhaled corticosteroids, smoking history), this being valid for both perennial and seasonal diseases during exposure to allergens. For the aspiration method, meta-regressions indicated that older age and a better pulmonary function were associated with a lower difference in nNO levels between patients with AR and controls, whereas an increasing aspiration flow was associated with a high effect size.

CONCLUSION

nNO levels are higher in AR, particularly when using high aspiration flows and in younger patients, who often perceive this condition as a source of disability. Further studies are needed to evaluate the usefulness of this biomarker for monitoring airway disorders and optimizing strategies in different settings (community, hospital, rehabilitation).

Proceedings of the 4th BEAT-PCD Conference and 5th PCD Training School

Primary ciliary dyskinesia (PCD) is an inherited ciliopathy leading to chronic suppurative lung disease, chronic rhinosinusitis, middle ear disease, sub-fertility and situs abnormalities. As PCD is rare, it is important that scientists and clinicians foster international collaborations to share expertise in order to provide the best possible diagnostic and management strategies. 'Better Experimental Approaches to Treat Primary Ciliary Dyskinesia' (BEAT-PCD) is a multidisciplinary network funded by EU COST Action (BM1407) to coordinate innovative basic science and clinical research from across the world to drive advances in the field. The fourth and final BEAT-PCD Conference and fifth PCD Training School were held jointly in March 2019 in Poznan, Poland. The varied program of plenaries, workshops, break-out sessions, oral and poster presentations were aimed to enhance the knowledge and skills of delegates, whilst also providing a collaborative platform to exchange ideas. In this final BEAT-PCD conference we were able to build upon programmes developed throughout the lifetime of the COST Action. These proceedings report on the conference, highlighting some of the successes of the BEAT-PCD programme.

International consensus guideline for reporting transmission electron microscopy results in the diagnosis of primary ciliary dyskinesia (BEAT PCD TEM Criteria)

Primary ciliary dyskinesia (PCD) is a heterogeneous genetic condition. European and North American diagnostic guidelines recommend transmission electron microscopy (TEM) as one of a combination of tests to confirm a diagnosis. However, there is no definition of what constitutes a defect or consensus on reporting terminology. The aim of this project was to provide an internationally agreed ultrastructural classification for PCD diagnosis by TEM.A consensus guideline was developed by PCD electron microscopy experts representing 18 centres in 14 countries. An initial meeting and discussion were followed by a Delphi consensus process. The agreed guideline was then tested, modified and retested through exchange of samples and electron micrographs between the 18 diagnostic centres.The final guideline a) provides agreed terminology and a definition of Class 1 defects which are diagnostic for PCD; b) identifies Class 2 defects which can indicate a diagnosis of PCD in combination with other supporting evidence; c) describes features which should be included in a ciliary ultrastructure report to assist multidisciplinary diagnosis of PCD; and d) defines adequacy of a diagnostic sample.This tested and externally validated statement provides a clear guideline for the diagnosis of PCD by TEM which can be used to standardise diagnosis internationally.

Nasal Nitric Oxide in Chronic Rhinosinusitis with or without Nasal Polyps: A Systematic Review with Meta-Analysis

Background and Aims: There has been a recent growing interest in the role of nasal nitric oxide (nNO) as a biomarker for osteomeatal complex obstruction in paranasal sinus diseases. By using meta-analysis, we systematically reviewed the literature to establish the possible link between nNO concentration and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP). Methods: We systematically searched the EMBASE, PubMed, Scopus, and Web of Science databases for related studies. Differences between controls and cases were reported as standardized mean difference (SMD), with 95% confidence intervals (95% CI), using the random-effects method. Results: We selected 23 articles for the final analysis: 15 with data on 461 CRSwNP patients and 384 healthy controls, 10 with data on 183 CRSsNP patients and 260 controls, and 14 studies on 372 CRSwNP and 297 CRSsNP patients. CRSwNP patients showed significantly lower nNO values when compared to both healthy controls (SMD: −1.495; 95% CI: −2.135, −0.854; p < 0.0001) and CRSsNP patients (SMD: −1.448; 95% CI: −2.046, −0.850; p < 0.0001). Sensitivity and subgroup analyses confirmed the results, which were further refined by regression models. They showed that an increasing aspiration flow is related to a greater difference in nNO levels between cases and control subjects. We also documented lower nNO levels in CRSsNP patients with respect to controls (SMD: −0.696; 95% CI: −1.189, −0.202; p = 0.006), being this result no longer significant when excluding patients in therapy with intranasal corticosteroids. As shown by regression models, the increased Lund–Mackay score indicates a high effect size. Conclusions: nNO levels are significantly lower in CRSwNP, especially when using higher aspiration flows. Additional studies are needed to define one single standardized method and normal reference values for nNO.

Diagnosis of Primary Ciliary Dyskinesia. An Official American Thoracic Society Clinical Practice Guideline

BACKGROUND

This document presents the American Thoracic Society clinical practice guidelines for the diagnosis of primary ciliary dyskinesia (PCD).

TARGET AUDIENCE

Clinicians investigating adult and pediatric patients for possible PCD.

METHODS

Systematic reviews and, when appropriate, meta-analyses were conducted to summarize all available evidence pertinent to our clinical questions. Evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach for diagnosis and discussed by a multidisciplinary panel with expertise in PCD. Predetermined conflict-of-interest management strategies were applied, and recommendations were formulated, written, and graded exclusively by the nonconflicted panelists. Three conflicted individuals were also prohibited from writing, editing, or providing feedback on the relevant sections of the manuscript.

RESULTS

After considering diagnostic test accuracy, confidence in the estimates for each diagnostic test, relative importance of test results studied, desirable and undesirable direct consequences of each diagnostic test, downstream consequences of each diagnostic test result, patient values and preferences, costs, feasibility, acceptability, and implications for health equity, the panel made recommendations for or against the use of specific diagnostic tests as compared with using the current reference standard (transmission electron microscopy and/or genetic testing) for the diagnosis of PCD.

CONCLUSIONS

The panel formulated and provided a rationale for the direction as well as for the strength of each recommendation to establish the diagnosis of PCD.

Cost-effectiveness analysis of three algorithms for diagnosing primary ciliary dyskinesia: a simulation study

Background

Primary Ciliary Dyskinesia (PCD) diagnosis relies on a combination of tests which may include (a) nasal Nitric Oxide (nNO), (b) High Speed Video Microscopy (HSVM) and (c) Transmission Electron Microscopy (TEM). There is variability in the availability of these tests and lack of universal agreement whether diagnostic tests should be performed in sequence or in parallel. We assessed three combinations of tests for PCD diagnosis and estimated net sensitivity and specificity as well as cost-effectiveness (CE) and incremental cost-effectiveness (ICE) ratios.

Methods and results

A hypothetical initial population of 1000 referrals (expected 320 PCD patients) was followed through a probabilistic decision analysis model which was created to assess the CE of three diagnostic algorithms (a) nNO + TEM in sequence, (b) nNO + HSVM in sequence and (c) nNO/HSVM in parallel followed, in cases with conflicting results, by confirmatory TEM (nNO/HSVM+TEM). Number of PCD patients identified, CE and ICE ratios were calculated using Monte Carlo simulations. Out of 320 expected PCD patients, 313 were identified by nNO/HSVM+TEM, 274 with nNO + HSVM and 198 with nNO + TEM. The nNO/HSVM+TEM had the highest mean annual cost (€209 K) followed by nNO + TEM (€150 K) and nNO + HSVM (€136 K). The nNO + HSVM algorithm dominated the nNO + TEM algorithm (less costly and more effective). The ICE ratio for nNO/HSVM+TEM was €2.1 K per additional PCD patient identified.

Conclusions

The diagnostic algorithm (nNO/HSVM+TEM) with parallel testing outperforms algorithms with tests in sequence. These findings, can inform the dialogue on the development of evidence-based guidelines for PCD diagnostic testing. Future research in understudied aspects of the disease, such as PCD-related quality of life and PCD-associated costs, is needed to help the better implementation of these guidelines across various healthcare systems.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1116-3) contains supplementary material, which is available to authorized users.

Wide phenotypic variability in RSPH9-associated primary ciliary dyskinesia: review of a case-series from Cyprus

Background

Primary ciliary dyskinesia (PCD) is an inherited ciliary motility disorder caused by mutations in at least 40 genes. RSPH9 gene mutations encoding aberrant radial spoke head proteins have been linked with PCD. The clinical spectrum extent of RSPH9 gene mutations remains to date largely unknown. We aimed to describe the diagnostic and clinical phenotype in a case-series of RSPH9-associated PCD.

Methods

We performed whole exome sequencing in suspect patients from Cyprus who on repeated cilia biopsies demonstrated loss of the central pair apparatus on Transmission Electron Microscopy (TEM) and rotary beating patterns on High Speed Video Microscopy (HSVM), compatible to findings described previously in PCD patients bearing pathogenic RSPH9 mutations. In cases confirmed by genetic testing, we reviewed diagnostic, demographic and clinical data, as well as anthropometric and spirometric measurements.

Results

We diagnosed 7 individuals (5 females) homozygous for the novel RSPH9 splice site mutation c.670+2T>C in intron 4, who originated from two families. Despite bearing the same genetic variant, patients presented a highly variable age (median 47.9 years; range, 6.6 to 51.4 years) and with a diverse clinical picture, all reporting a history of chronic or recurrent wet cough (100%), and at varying frequencies neonatal respiratory distress (43%), chronic rhinosinusitis (71%), and wheezing (43%). Complications such as bronchiectasis (71%), history of pneumonia(s) (57%) and surgical interventions (43%) clustered in some patients displaying typical PCD, but not in others with milder phenotypes. BMI-z scores (median: 0.53; range, -0.69 to 1.52), FEV1-z scores (median: -0.37; range: -1.79 to 0.22) and FVC z-scores (median: -0.80; range: -2.01 to 0.36) were on average within the normal range, although slightly reduced.

Conclusions

In conclusion, RSPH9-associated PCD disease demonstrates wide phenotypic variability. In some cases, mild clinical presentation is difficult to justify diagnostic work-up, highlighting the importance of wider adoption of genetic diagnostics. Larger studies are needed to assess variability of clinical spectrum associated to alterations of PCD genes.

Nasal Nitric Oxide in Primary Immunodeficiency and Primary Ciliary Dyskinesia: Helping to Distinguish Between Clinically Similar Diseases

PURPOSE

Primary ciliary dyskinesia (PCD) is a rare disorder of the mucociliary clearance leading to recurrent upper and lower respiratory tract infections. PCD is difficult to clinically distinguish from other entities leading to recurrent oto-sino-pulmonary infections, including primary immunodeficiency (PID). Nasal nitric oxide (nNO) is a sensitive and specific diagnostic test for PCD, but it has not been thoroughly examined in PID. Past publications have suggested an overlap in nNO levels among subjects with PCD and PID. We sought to determine if nNO measurements among patients diagnosed with PID would fall significantly above the established PCD diagnostic cutoff value of 77 nL/min.

METHODS

Children > 5 years old and adults with definitive PID or PCD diagnoses were recruited from outpatient subspecialty clinics. Participants underwent nNO testing by standardized protocol using a chemiluminescence analyzer and completed a questionnaire concerning their chronic oto-sino-pulmonary symptoms, including key clinical criteria specific to diagnosed PCD (neonatal respiratory distress at term birth, year-round cough or nasal congestion starting before 6 months of age, any organ laterality defect).

RESULTS

Participants included 32 patients with PID, 27 patients with PCD, and 19 healthy controls. Median nNO was 228.9.1 nL/min in the PID group, 19.7 nL/min in the PCD group, and 269.4 in the healthy controls (p < 0.0001). Subjects with PCD were significantly more likely to report key clinical criteria specific to PCD, but approximately 25% of PID subjects also reported at least 1 of these key clinical criteria (mainly year-round cough or nasal congestion).

CONCLUSIONS

While key clinical criteria associated with PCD often overlap with the symptoms reported in PID, nNO measurement by chemiluminescence technology allows for effective discrimination between PID and PCD.

Homozygous missense mutation L673P in adenylate kinase 7 (AK7) leads to primary male infertility and multiple morphological anomalies of the flagella but not to primary ciliary dyskinesia

Motile cilia and sperm flagella share an extremely conserved microtubule-based cytoskeleton, called the axoneme, which sustains beating and motility of both organelles. Ultra-structural and/or functional defects of this axoneme are well-known to cause primary ciliary dyskinesia (PCD), a disorder characterized by recurrent respiratory tract infections, chronic otitis media, situs inversus, male infertility and in most severe cases, hydrocephalus. Only recently, mutations in genes encoding axonemal proteins with preferential expression in the testis were identified in isolated male infertility; in those cases, individuals displayed severe asthenozoospermia due to Multiple Morphological Abnormalities of the sperm Flagella (MMAF) but not PCD features. In this study, we performed genetic investigation of two siblings presenting MMAF without any respiratory PCD features, and we report the identification of the c.2018T > G (p.Leu673Pro) transversion in AK7, encoding an adenylate kinase, expressed in ciliated tissues and testis. By performing transcript and protein analyses of biological samples from individual carrying the transversion, we demonstrate that this mutation leads to the loss of AK7 protein in sperm cells but not in respiratory ciliated cells, although both cell types carry the mutated transcript and no tissue-specific isoforms were detected. This work therefore, supports the notion that proteins shared by both cilia and sperm flagella may have specific properties and/or function in each organelle, in line with the differences in their mode of assembly and organization. Overall, this work identifies a novel genetic cause of asthenozoospermia due to MMAF and suggests that in humans, more deleterious mutations of AK7 might induce PCD.

Measurement of fractional exhaled nitric oxide and nasal nitric oxide in male patients with obstructive sleep apnea

Objective

Airway inflammation plays an important role in obstructive sleep apnea (OSA); exhaled nitric oxide is regarded as a noninvasive marker of airway inflammation. The aim of this study was to evaluate fractional exhaled nitric oxide (FeNO) and nasal nitric oxide (nNO) in patients with OSA.

Methods

Seventy-five patients with OSA and 30 health controls were enrolled in this study. FeNO and nNO were measured before and after sleep. Nasal lavage was performed in 31 non-smoking individuals immediately after NO measurement in the morning. The sample of nasal lavage was taken for cell classification and analyzing interleukin 6 (IL-6) and interleukin 8 (IL-8).

Results

Both FeNO and nNO were significantly higher in OSA (before sleep FeNO 21.08 ± 8.79 ppb vs.16.90 ± 6.86 ppb, p = 0.022; after sleep FeNO 25.57 ± 15.58 ppb vs.18.07 ± 6.25 ppb, p = 0.003; before sleep nNO 487.03 ± 115.83 ppb vs. 413.37 ± 73.10 ppb, p = 0.001; after sleep nNO 550.07 ± 130.24 ppb vs. 460.43 ± 109.77 ppb, p < 0.001). Furthermore, in non-smoking OSA, nNO levels were positively correlated with apnea hypopnea index (AHI) and average decrease of pulse arterial oxygen saturation (SpO₂); after sleep, nNO was also positively associated to recording time with SpO₂ < 90% and negatively associated to minimum SpO₂. Both before and after sleep nNO levels were positively correlated with the percentage of neutrophils in nasal lavage (r = 0.528, p = 0.014; r = 0.702, p < 0.001, respectively). Additionally, before sleep nNO was also positively associated with IL-6 (r = 0.586, p = 0.005) and IL-8 (r = 0.520, p = 0.016) concentration.

Conclusion

This study sustains the presence of airway inflammation in OSA patients with the increase of FeNO and nNO. The data suggests nNO might have greater value than FeNO since it positively correlated with OSA severity, and nNO is a potential bio-marker of nasal inflammation in non-smoking OSA patients.

Electronic supplementary material

The online version of this article (10.1007/s11325-018-1760-1) contains supplementary material, which is available to authorized users.

Motile Ciliary Disorders in Chronic Airway Inflammatory Diseases: Critical Target for Interventions

PURPOSE OF REVIEW

Impaired mucociliary clearance has been implicated in chronic upper and lower airway inflammatory diseases (i.e., allergic and non-allergic rhinitis, chronic rhinosinusitis with or without nasal polyps and asthma). How motile ciliary disorders (impaired ciliogenesis, ciliary beating and ultrastructural defects) are implicated in chronic airway inflammatory diseases is not fully understood. Elaboration of the role of motile ciliary disorders may serve as therapeutic targets for improving mucociliary clearance, thereby complementing contemporary disease management.

RECENT FINDINGS

We have summarized the manifestations of motile ciliary disorders and addressed the underlying associations with chronic airway inflammatory diseases. A panel of established and novel diagnostic tests and therapeutic interventions are outlined. Physicians should be vigilant in screening for motile ciliary disorders, particularly in patients with co-existing upper and lower airway inflammatory diseases. Proper assessment and treatment of motile ciliary disorders may have added value to the management and prevention of chronic airway inflammatory diseases.

Infant nasal nitric oxide over time: natural evolution and impact of respiratory tract infection

Nasal nitric oxide (NO) discriminates between patients with primary ciliary dyskinesia (PCD) and healthy individuals. We report feasibility of measurement and natural evolution of nasal NO and upon the impact of respiratory tract infection (RTI) on nasal NO in healthy infants (HI), followed from birth until age 2 years, with comparison to nasal NO in infant PCD.Tidal-breathing nasal NO measurements were performed at scheduled visits at 2 weeks old and at 4, 8, 12, 18 and 24 months old, with extra visits during RTIs. Historical nasal NO measurements for infant PCD were included for comparison.Altogether, 224 nasal NO measurements were performed in 44 enrolled infants. Median newborn nasal NO was 46 ppb (interquartile range (IQR) 29-69 ppb), increasing at a rate of 5.4% per month up to 283 ppb (IQR 203-389 ppb) at the age of 2 years. RTIs in 27 out of 44 infants temporarily suppressed nasal NO by 79%. Values for nasal NO in seven infants with PCD ranged from 6-80 ppb. The success rate to accept nasal NO sampling was 223 out of 224 measurements (99.6%).Tidal-breathing nasal NO measurement was indeed feasible in infancy and nasal NO in HI increased significantly up to 2 years of age, in opposition to nasal NO in PCD cases, which stayed low past 2 years of age. RTI episodes caused marked, temporary reductions in nasal NO in HI indistinguishable from that in infant PCD, suggesting that nasal NO should be measured in RTI-free intervals.

Accuracy of Nasal Nitric Oxide Measurement as a Diagnostic Test for Primary Ciliary Dyskinesia. A Systematic Review and Meta-analysis

RATIONALE

Primary ciliary dyskinesia (PCD) is a rare disorder causing chronic otosinopulmonary disease, generally diagnosed through evaluation of respiratory ciliary ultrastructure and/or genetic testing. Nasal nitric oxide (nNO) measurement is used as a PCD screening test because patients with PCD have low nNO levels, but its value as a diagnostic test remains unknown.

OBJECTIVES

To perform a systematic review to assess the utility of nNO measurement (index test) as a diagnostic tool compared with the reference standard of electron microscopy (EM) evaluation of ciliary defects and/or detection of biallelic mutations in PCD genes.

DATA SOURCES

Ten databases were searched for reference sources from database inception through July 29, 2016.

DATA EXTRACTION

Study inclusion was limited to publications with rigorous nNO index testing, reference standard diagnostic testing with EM and/or genetics, and calculable diagnostic accuracy information for cooperative patients (generally >5 yr old) with high suspicion of PCD.

SYNTHESIS

Meta-analysis provided a summary estimate for sensitivity and specificity and a hierarchical summary receiver operating characteristic curve. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess study quality, and Grading of Recommendations Assessment, Development, and Evaluation was used to assess the certainty of evidence. In 12 study populations (1,344 patients comprising 514 with PCD and 830 without PCD), using a reference standard of EM alone or EM and/or genetic testing, summary sensitivity was 97.6% (92.7-99.2) and specificity was 96.0% (87.9-98.7), with a positive likelihood ratio of 24.3 (7.6-76.9), a negative likelihood ratio of 0.03 (0.01-0.08), and a diagnostic odds ratio of 956.8 (141.2-6481.5) for nNO measurements. After studies using EM alone as the reference standard were excluded, the seven studies using an extended reference standard of EM and/or genetic testing showed a summary sensitivity of nNO measurements of 96.3% (88.7-98.9) and specificity of 96.4% (85.1-99.2), with a positive likelihood ratio of 26.5 (5.9-119.1), a negative likelihood ratio of 0.04 (0.01-0.12), and a diagnostic odds ratio of 699.3 (67.4-7256.0). Certainty of the evidence was graded as moderate.

CONCLUSIONS

nNO is a sensitive and specific test for PCD in cooperative patients (generally >5 yr old) with high clinical suspicion for this disease. With a moderate level of evidence, this meta-analysis confirms that nNO testing using velum closure maneuvers has diagnostic accuracy similar to EM and/or genetic testing for PCD when cystic fibrosis is ruled out. Thus, low nNO values accompanied by an appropriate clinical phenotype could be used as a diagnostic PCD test, though EM and/or genetics will continue to provide confirmatory information.

Multiple breath washout in pediatric patients after lung transplantation

Forced expiratory volume in 1 second (FEV₁ ) from spirometry is the most commonly used parameter to detect early allograft dysfunction after lung transplantation (LTx). There are concerns regarding its sensitivity. Nitrogen-multiple breath washout (N₂ -MBW) is sensitive at detecting early global (lung clearance index [LCI]) and acinar (S_acin ) airway inhomogeneity. We investigated whether N₂ -MBW indices indicate small airways pathology after LTx in children with stable spirometry. Thirty-seven children without bronchiolitis obliterans syndrome [BOS] at a median of 1.6 (0.6-3.0) years after LTx underwent N₂ -MBW and spirometry, 28 of those on 2 occasions (≤6 months apart) during clinically stable periods. Additional longitudinal data (11 and 8 measurements, respectively) are provided from 2 patients with BOS. In patients without BOS, LCI and S_acin were significantly elevated compared with healthy controls. LCI was abnormal at the 2 test occasions in 81% and 71% of patients, respectively, compared with 30% and 39% of patients with abnormal FEV₁ /forced vital capacity (FVC). Correlations of LCI with FEV₁ /FVC (r = 0.1, P = .4) and FEV₁ (r = -0.1, P = .6) were poor. N₂ -MBW represents a sensitive and reproducible tool for the early detection of airways pathology in stable transplant recipients. Moreover, indices were highly elevated in both patients with BOS. Spirometry and LCI showed poor correlation, indicating distinct and complementary physiologic measures.

Low Nasal NO in Congenital Heart Disease With Systemic Right Ventricle and Postcardiac Transplantation

Background

NO bioavailability has not been systematically examined in congenital heart disease (CHD). To assess NO in patients with CHD, we measured nasal NO (nNO) generated by the nasal epithelia, given blood NO is difficult to measure (half‐life, <2 ms). Given NO's role in hemodynamic regulation and the association of NO bioavailability with heart failure risk, we hypothesized NO levels may differ with varying severity of CHD physiologic characteristics.

Methods and Results

Six‐hundred eighteen subjects, 483 with CHD and 135 controls, had nNO measured noninvasively via the nares using American Thoracic Society/European Respiratory Society guidelines. Subjects were dichotomized as having low or normal nNO based on age‐specific cutoff values. Prevalence of low nNO was examined by various CHD physiologic feature types. Low nNO was more prevalent with CHD than controls (odds ratio, 2.28; P=0.001). A logistic regression model showed overall significance (P=0.035) for single ventricle, systemic right ventricle, ventricular dysfunction, oxygen desaturation, and heterotaxy predicting low nNO, with systemic right ventricle independently having twice the odds of low nNO (odds ratio, 2.04; P=0.014). Patients with low nNO had a higher risk of experiencing heart transplant or death (hazard ratio, 2.75; P=0.048), and heart transplant recipients (N=16) exhibited 5 times the odds of low nNO (69% versus 30%; odds ratio, 5.1; P=0.001).

Conclusions

Patients with CHD have increased prevalence of low nNO, with highest odds seen with systemic right ventricle and heart transplant. Further studies are needed to investigate heart failure risks in patients with CHD with left versus right systemic ventricle physiologic characteristics and utility of low nNO for predicting heart failure risk.

How to use nasal nitric oxide in a child with suspected primary ciliary dyskinesia

Measuring nasal nitric oxide (nNO) is increasingly used as part of testing for primary ciliary dyskinesia (PCD). The diagnosis of PCD is often delayed until after bronchiectasis is established and auditory damage has occurred. It is important that all paediatricians are aware of clinical features that are suggestive of PCD that should prompt diagnostic testing. nNO levels are recognised to be low in people with PCD and results generated by static chemiluminescence analysers using velum closure technique in older children have good sensitivity and specificity. However, to conclusively rule PCD in or out, further tests of ciliary function are required and assessment of cilia ultrastructure, immunohistochemistry studies and genotyping may also be indicated. These tests are more complex, invasive and expensive than nNO. nNO is less well studied in younger children where tidal breathing measurements are required. Portable nitric oxide analysers are also increasingly used in practice. This paper discusses when to consider PCD as a possible diagnosis in a child along with the indications, physiological and technical background and clinical utility of nNO as a test for PCD in children.

The effect of l-Arginine on Ciliary Beat Frequency in PCD patients, non-PCD respiratory patients and healthy controls

OBJECTIVES

Few studies have examined the potentially therapeutic effect of increasing the production of endogenous nitric oxide (NO) in Primary Ciliary Dyskinesia (PCD) and other chronic respiratory conditions. Nasal NO is low in PCD and has been found to correlate with compromised Ciliary Beat Frequency (CBF). In this study we assessed the effect of increasing l-Arginine, as the substrate of NO synthases, on CBF in biopsies of human respiratory ciliated epithelium.

METHODOLOGY

A total of 28 suspect cases with chronic respiratory manifestations referred for PCD diagnostic testing and 8 healthy controls underwent nasal brushing. Obtained epithelial cells were divided between three culture medium 199 solutions, containing different levels of l-Arginine (0.33 mM as baseline, 1 mM and 10 Mm as increased levels). CBF measurements were obtained at 37 °C and 25 °C at 1, 3 and 24 h after sample acquisition.

RESULTS

Among a total of 36 recruited subjects, 8 had PCD confirmed (PCD n = 8), 20 had PCD excluded (non-PCD n = 20) and 8 were healthy controls (Healthy Controls = 8). Among PCD subjects, ciliary motility was characterized by rotational (n = 5) or dyskinetic (n = 3) beating. At 37 °C, compared to baseline, higher levels of l-Arginine resulted in up to 9% CBF increase at 1 h (p = 0.007), up to 9% CBF increase at 3 h (p < 0.001) and up to 12% CBF increase at 24 h (p = 0.002). Similar although smaller scale increases were recorded at 25 °C. The effect of l-Arginine was time dependent (interaction p = 0.002) and was similar in PCD patients, non-PCD chronic respiratory patients and healthy controls (interaction p = 0.800).

CONCLUSIONS

l-Arginine increases CBF and merits to be evaluated as a potential stimulator of mucociliary clearance in chronic respiratory conditions and congenital ciliary disorders with residual motility. Larger human studies are needed to confirm these findings.

Clinical care for primary ciliary dyskinesia: current challenges and future directions

Primary ciliary dyskinesia (PCD) is a rare genetic disease that affects the motility of cilia, leading to impaired mucociliary clearance. It is estimated that the vast majority of patients with PCD have not been diagnosed as such, providing a major obstacle to delivering appropriate care. Challenges in diagnosing PCD include lack of disease-specific symptoms and absence of a single, "gold standard", diagnostic test. Management of patients is currently not based on high-level evidence because research findings are mostly derived from small observational studies with limited follow-up period. In this review, we provide a critical overview of the available literature on clinical care for PCD patients, including recent advances. We identify barriers to PCD research and make suggestions for overcoming challenges.

Diagnosis of primary ciliary dyskinesia: summary of the ERS Task Force report

Key points

Primary ciliary dyskinesia (PCD) is a genetically and clinically heterogeneous disease characterised by abnormal motile ciliary function.

There is no “gold standard” diagnostic test for PCD.

The European Respiratory Society (ERS) Task Force Guidelines for diagnosing PCD recommend that patients should be referred for diagnostic testing if they have several of the following features: persistent wet cough; situs anomalies; congenital cardiac defects; persistent rhinitis; chronic middle ear disease with or without hearing loss; or a history, in term infants, of neonatal upper and lower respiratory symptoms or neonatal intensive care admission.

The ERS Task Force recommends that patients should be investigated in a specialist PCD centre with access to a range of complementary tests: nasal nitric oxide, high-speed video microscopy analysis and transmission electron microscopy. Additional tests including immunofluorescence labelling of ciliary proteins and genetic testing may also help determine the diagnosis.

Educational aims

This article is intended for primary and secondary care physicians interested in primary ciliary dyskinesia (PCD), i.e. those who identify patients for testing, and those involved in diagnosing and managing PCD patients. It aims:

to inform readers about the new European Respiratory Society Task Force Guidelines for diagnosing patients with PCD

to enable primary and secondary care physicians to: identify patients who need diagnostic testing; understand the diagnostic tests that their patients will undergo, the results of the tests and their limitations; and ensure that appropriate care is subsequently delivered.

What primary and secondary care physicians should know about the diagnosis of primary ciliary dyskinesiahttp://ow.ly/obix30drts1

Occupational rhinoconjunctivitis caused by the common indoor plant, Hoya compacta

BACKGROUND

Allergic reactions to the common house plant Hoya compacta (HC) have not previously been described.

AIMS

To confirm HC as the cause of rhinoconjunctivitis in three horticultural workers.

METHODS

Greenhouse working conditions were reproduced in our challenge chamber.

RESULTS

All three cases developed rhinoconjunctivitis when working with HC plants. A control challenge was performed in two cases with iceberg lettuce causing no symptoms. Nasal volume measured by acoustic rhinometry (AR) fell after all three active challenges, but also after one of the control challenges.

CONCLUSIONS

Our study confirms that HC may cause occupational rhinoconjunctivitis and asthma through a Type I hypersensitivity reaction. Specific inhalation challenges, nasal nitric oxide measurement and AR may be useful additional tools in supporting such diagnoses for occupational physicians to consider.

The Saudi Thoracic Society guidelines for diagnosis and management of noncystic fibrosis bronchiectasis

This is the first guideline developed by the Saudi Thoracic Society for the diagnosis and management of noncystic fibrosis bronchiectasis. Local experts including pulmonologists, infectious disease specialists, thoracic surgeons, respiratory therapists, and others from adult and pediatric departments provided the best practice evidence recommendations based on the available international and local literature. The main objective of this guideline is to utilize the current published evidence to develop recommendations about management of bronchiectasis suitable to our local health-care system and available resources. We aim to provide clinicians with tools to standardize the diagnosis and management of bronchiectasis. This guideline targets primary care physicians, family medicine practitioners, practicing internists and respiratory physicians, and all other health-care providers involved in the care of the patients with bronchiectasis.

A European Respiratory Society technical standard: exhaled biomarkers in lung disease

Breath tests cover the fraction of nitric oxide in expired gas (F_eNO), volatile organic compounds (VOCs), variables in exhaled breath condensate (EBC) and other measurements. For EBC and for F_eNO, official recommendations for standardised procedures are more than 10 years old and there is none for exhaled VOCs and particles. The aim of this document is to provide technical standards and recommendations for sample collection and analytic approaches and to highlight future research priorities in the field. For EBC and F_eNO, new developments and advances in technology have been evaluated in the current document. This report is not intended to provide clinical guidance on disease diagnosis and management.Clinicians and researchers with expertise in exhaled biomarkers were invited to participate. Published studies regarding methodology of breath tests were selected, discussed and evaluated in a consensus-based manner by the Task Force members.Recommendations for standardisation of sampling, analysing and reporting of data and suggestions for research to cover gaps in the evidence have been created and summarised.Application of breath biomarker measurement in a standardised manner will provide comparable results, thereby facilitating the potential use of these biomarkers in clinical practice.

Cephalosporin-3'-Diazeniumdiolate NO Donor Prodrug PYRRO-C3D Enhances Azithromycin Susceptibility of Nontypeable Haemophilus influenzae Biofilms

PYRRO-C3D is a cephalosporin-3-diazeniumdiolate nitric oxide (NO) donor prodrug designed to selectively deliver NO to bacterial infection sites. The objective of this study was to assess the activity of PYRRO-C3D against nontypeable Haemophilus influenzae (NTHi) biofilms and examine the role of NO in reducing biofilm-associated antibiotic tolerance. The activity of PYRRO-C3D on in vitro NTHi biofilms was assessed through CFU enumeration and confocal microscopy. NO release measurements were performed using an ISO-NO probe. NTHi biofilms grown on primary ciliated respiratory epithelia at an air-liquid interface were used to investigate the effects of PYRRO-C3D in the presence of host tissue. Label-free liquid chromatography-mass spectrometry (LC/MS) proteomic analyses were performed to identify differentially expressed proteins following NO treatment. PYRRO-C3D specifically released NO in the presence of NTHi, while no evidence of spontaneous NO release was observed when the compound was exposed to primary epithelial cells. NTHi lacking β-lactamase activity failed to trigger NO release. Treatment significantly increased the susceptibility of in vitro NTHi biofilms to azithromycin, causing a log fold reduction (10-fold reduction or 1-log-unit reduction) in viability (P < 0.05) relative to azithromycin alone. The response was more pronounced for biofilms grown on primary respiratory epithelia, where a 2-log-unit reduction was observed (P < 0.01). Label-free proteomics showed that NO increased expression of 16 proteins involved in metabolic and transcriptional/translational functions. NO release from PYRRO-C3D enhances the efficacy of azithromycin against NTHi biofilms, putatively via modulation of NTHi metabolic activity. Adjunctive therapy with NO mediated through PYRRO-C3D represents a promising approach for reducing biofilm-associated antibiotic tolerance.

Diagnosis of primary ciliary dyskinesia: potential options for resource-limited countries

Primary ciliary dyskinesia is a genetic disease of ciliary function leading to chronic upper and lower respiratory tract symptoms. The diagnosis is frequently overlooked because the symptoms are nonspecific and the knowledge about the disease in the primary care setting is poor. Additionally, none of the available tests is accurate enough to be used in isolation. These tests are expensive, and need sophisticated equipment and expertise to analyse and interpret results; diagnosis is therefore only available at highly specialised centres. The diagnosis is particularly challenging in countries with limited resources due to the lack of such costly equipment and expertise.

In this review, we discuss the importance of early and accurate diagnosis especially for countries where the disease is clinically prevalent but diagnostic tests are lacking. We review the diagnostic tests available in specialised centres (nasal nitric oxide, high-speed video microscopy, transmission electron microscopy, immunofluorescence and genetics). We then consider modifications that might be considered in less well-resourced countries whilst maintaining acceptable accuracy.